IL-1β transgenic mouse model of inflammation driven esophageal and oral squamous cell carcinoma

Chronic inflammation is integral to the development of esophageal adenocarcinoma (EAC) and esophageal squamous cell carcinoma (ESCC), although the latter has not been associated with reflux esophagitis. The L2-IL-1β transgenic mice, expressing human interleukin (IL)-1β in the oral, esophageal and forestomach squamous epithelia feature chronic inflammation and a stepwise development of Barrett’s esophagus-like metaplasia, dysplasia and adenocarcinoma at the squamo-columnar junction. However, the functional consequences of IL-1β-mediated chronic inflammation in the oral and esophageal squamous epithelia remain elusive. We report for the first time that in addition to the previously described Barrett’s esophagus-like metaplasia, the L2-IL-1β mice also develop squamous epithelial dysplasia with progression to squamous cell carcinoma (SCC) in the esophagus and the tongue. L2-IL-1β showed age-dependent progression of squamous dysplasia to SCC with approximately 40% (n = 49) and 23.5% (n = 17) incidence rates for esophageal and tongue invasive SCC respectively, by 12–15 months of age. Interestingly, SCC development and progression in L2-IL-1β was similar in both Germ Free (GF) and Specific Pathogen Free (SPF) conditions. Immunohistochemistry revealed a T cell predominant inflammatory profile with enhanced expression of Ki67, Sox2 and the DNA double-strand break marker, γ-H2AX, in the dysplastic squamous epithelia of L2-IL-1β mice. Pro-inflammatory cytokines, immunomodulatory players, chemoattractants for inflammatory cells (T cells, neutrophils, eosinophils, and macrophages) and oxidative damage marker, iNOS, were significantly increased in the esophageal and tongue tissues of L2-IL-1β mice. Our recent findings have expanded the translational utility of the IL-1β mouse model to aid in further characterization of the key pathways of inflammation driven BE and EAC as well as ESCC and Oral SCC.

of the extent of surface epithelial degeneration, tethering, erosions to full thickness ulcerations and associated glandular atrophy as absent (score of 0), rare (score of 1), frequent (score of 2), moderate with surface erosions with gland atrophy (score of 3) and severe with full thickness mucosal ulcerations, gland atrophy, and fibrosis (score of 4).
Hyalinosis is a non-specific change characterized by the accumulation of brightly eosinophilic droplets and/or extracellular crystals and was scored on the basis of the extent of gastric mucosal involvement (30) as absent (score of 0), minimal with only surface intracellular epithelial glassy red hyaline material (score of 1), mild with presence of both intracellular hyaline material and/or occasional extracellular hyaline crystals, moderate with frequent extracellular crystals (score of 3), and severe with diffuse hyaline change/crystals in the scored segment (score of 4). Oxyntic atrophy was defined as a reduction in the mass of chief and parietal cells in the gastric corpus segments and graded on the extent of loss via cell loss and/or metaplastic transformation. Oxyntic atrophy in the different corpus segments were scored as no oxyntic loss/atrophy (score of 0), minimal involving loss/atrophy of less than 25% of oxyntic cells (score of 1), mild with loss of approximately 26-50% of oxyntic cells (score of 2), moderate involving loss/atrophy of approximately 51-75% of oxyntic cells (score 3), and severe with more than 75% to complete loss of oxyntic cells, parietal and chief cells (score of 4).
Epithelial hyperplasia was scored on the basis of increased gastric mucosal thickness by virtue of proliferation of surface foveolar-type epithelium and/or antral-type glandular units and appropriately graded in relation to the extent of oxyntic loss. Epithelial hyperplasia was scored on the basis of increased length/depth of foveolar lining epithelium and/or glandular size/length as normal (score of 0), minimal (~1.5 times normal length/size, score of 1), mild (~2 times normal length/size, score of 2), moderate (~3 times normal length/size, score of 3), and severe (≥ 4 times normal length/size). Mucous metaplasia reflects a morphological change in appearance of glandular epithelium resulting from expansion of gastric mucous neck cells (PAS+/Alcian blue/TFF2 +) with foamy cytoplasm and marginated nucleus resembling Brunner's glands and usually secreting a mixture of neutral and acidic mucins in the gastric corpus mucosa. Pseudopyloric metaplasia is a preneoplastic change defined as replacement of the oxyntic mucosa by glands resembling antral phenotype with cells being more columnar and lacking typical cytoplasmic granules of oxyntic cells as well as the absence of cytoplasmic mucous appearance of mucous metaplasia. Both mucous metaplasia and pseudopyloric metaplasia were scored in the different corpus compartments on the basis of extent of oxyntic cell transformation as none (score of 0), minimal (rarely present, score of 1), mild with involvement of less than 1/3 rd of corpus segment (score of 2), moderate with involvement of 1/3 rd to 2/3 rd of corpus segment (score of 3), and severe with involvement of more than 2/3 rd of scored corpus segment.
Gastric epithelial dysplasia is histologically an unequivocal neoplastic change without evidence of stromal invasion occurring in sessile, flat, depressed or elevated/polypoid mucosal lesions and is defined by both architectural abnormalities (haphazard glandular arrangement, loss of vertical orientation, back-to-back gland associations, branching, infoldings, and piling up of cells) and cytological atypia (cellular pleomorphism, anisocytosis, anisokaryosis, ill-defined cellular junctions, loss of nuclear polarity, pencil or cigar shaped nuclei, hyperchromatic nuclei, increased nuclearcytoplasmic (N-C) ratio, visible mitosis, bizarre mitotic figures) (30). The term gastric adenoma was restricted to well demarcated or circumscribed, polypoid or raised nodular lesions comprising of tubular and/or villous structures, lined by dysplastic epithelium.

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Dysplasia/neoplasia was graded on its extent and severity of changes as follows: score of 0 for normal or mild simple epithelial hyperplasia with no atypia; score of 1 for one or few epithelial hyperplastic foci with mild architectural atypia (equivalent to indefinite for dysplasia or reactive epithelium); a score of 2 for atypical hyperplasia comprising of coalescing proliferative epithelial lesions with glandular architectural abnormalities (equivalent to indefinite for dysplasia); a score of 2.5 for low grade dysplasia/intraepithelial neoplasia or low grade adenoma and all of these proliferative lesions were defined by severe glandular architectural abnormalities and borderline cytological atypia; a score of 3 is equivalent to high grade dysplasia/intraepithelial neoplasia or a high grade adenoma characterized by severe architectural and cytological atypia; a score of 3.5 for intramucosal invasive neoplasia (intramucosal carcinoma) characterized by high grade dysplastic lesions with unequivocal invasion into the lamina propria or muscularis mucosa (dysplasia score of 3.5; and a score of 4 for submucosal invasive neoplasia (submucosal carcinoma) for true unequivocal invasion into the gastric submucosa or beyond.